In continuing the study of the conditions under which tactile patterns are most accurately and speedily recognized, this project is aimed at problems of both a basic and applied character. On the basic side, the problem of suitability of different skin areas for information processing persists, and this will be taken up in the grant period by direct attack. Selected body sites will be examined in both hearing and deaf populations for standard psychophysical functions, including but not restricted to absolute and differential thresholds for intensity and rate, spatial and temporal limens for pulses, magnitude estimation for intensity, and pattern recognition at various levels of complexity. Further work on the problems of pattern recognition will be done using the locally constructed tactile matrices for the palm and thigh, and the Optacon fingertip display recently acquired. Comparisons among these areas for a variety of processing capabilities are now possible, including growth of loudness with increasing number of vibrators, and the problem of pattern discrimination with increasing communality of elements between pairs. There will continue to be an analysis of the saltation effect, discovered in this laboratory. Of special interest is the variation of the apparent position of the saltatory phantom with repeated exposure found in the visual system, and to be searched for in the cutaneous sense. In addition, the primary determinants of the degree of saltatory leap, viz., locus, time, and intensity, will be examined for their relative influence on saltation in selected body sites. It has been for some time the orientation of the Princeton Cutaneous Project to attempt to balance the basic and applied aspects of empirical inquiry. The comparative fidelity of transmission of speech information by single- and multi-channel vibrators is an applied research effort of the laboratory that serves to supply information to developers and other investigators while at the same time presenting the investigators of this project with questions that may lead to basic research work. The aim and hope of this approach is to seve the medical sciences with two hands, so to speak: providing the basic information on normal mechanisms of information processing by the skin, while suggesting means by which the mechanisms may replace those in other senses that are undeveloped or lost.